NEW YORK >> Public hospitals in New York City are so concerned about Ebola, they’ve secretly been sending actors with mock symptoms into emergency rooms to test how well the triage staffs identify and isolate possible cases.

A small Ohio hospital has hung up signs imploring patients to let nurses know immediately if they have traveled recently to West Africa.

And across the U.S., one of the nation’s largest ambulance companies has put together step-by-step instructions for wrapping the interior of a rig with plastic sheeting.

There hasn’t been a single confirmed case of an Ebola infection happening on U.S. soil; the case confirmed in Dallas involves a man who, like several health care workers treated in the U.S., contracted the virus in Liberia. But health care providers are worried enough to take a wide variety of precautions.

It isn’t yet clear whether these preparations are overkill, or not nearly enough.

But health care experts say that at the very least, the scare is providing a chance to reinforce and test infection control procedures.

“The attention has been, in a sad way, very helpful,” said Dr. Richard Wenzel, an epidemiologist at Virginia Commonwealth University and a former president of the International Society for Infectious Diseases.

Even small hospitals far from international travel hubs should be reviewing protocols and screening questions, and potentially buying protective equipment such as face masks and protective suits, he said. This will help them avoid repeating the mistakes of Dallas, where a Liberian man with Ebola symptoms was sent away despite telling a hospital staffer he had traveled from Africa, and potentially infected many others before he was readmitted two days later.

“The debacle in Texas should stimulate improved awareness and responses,” Wenzel said.

A growing number of false alarms are already giving hospitals around the country ample opportunities to test infection control procedures.

In New York, 24 patients screened for Ebola have been put into isolation over the past eight weeks in city-owned hospitals, according to Dr. Ross Wilson, the chief medical officer at the New York City Health and Hospitals Corporation. None had the disease (some had malaria and one had typhoid), but Wilson said isolating potential cases as quickly as possible is essential to keep the virus from spreading.

“We’re taking this very seriously,” he said.

Emergency room staffers have been confronted with actors to test their triage measures, and some have been retrained on how to properly put on and remove protective gear, Wilson said.

At the city’s flagship Bellevue Hospital Center, technicians are assembling a lab to exclusively handle Ebola blood tests, keeping samples from contaminating other equipment, and a small number of beds are ready and waiting in an isolation ward for any confirmed cases.

New York City’s 911 operators have been told to ask people who describe Ebola-like symptoms and ask for ambulances if they’ve traveled to West Africa recently. That question is also becoming the norm at AMR, which operates private ambulances in 40 states.

It has told its staff of 19,000 paramedics and EMTs that if patients with these symptoms answer yes, they must alert other health authorities and put on extra protective gear, including shoe coverings, a mask and goggles.

“We don’t want to respond with a presumption that everyone in the field has Ebola,” said Dr. Ed Racht, AMR’s chief medical officer. “The idea is, if the travel question is positive with the symptoms, it gives us a yellow flag … It doesn’t mean immediately putting on the space suits.”

That said, the company has issued step-by-step instructions for using plastic sheeting, garbage bags and duct tape to protect the ambulance and driver from patients with the virus. Step No. 2: “Place sheeting on the floor of the rig and affix to bench seat, jump seat and walls to create a bowl affect in an effort to channel any body fluids toward the center of the floor causing fluids to collect in one area.”

A more commonplace precaution is in place at the Mercer County Community Hospital in Coldwater, Ohio, a village of 4,400 people near the Indiana state border. Nicole Pleiman, an infection prevention and control nurse, said the hospital posted signs at entrances a month ago telling patients to notify the staff immediately if they’ve traveled recently to African countries hit by the outbreak.

“We will definitely revisit that to see if we need to do anything additional,” she said.

And three major hospitals in Dallas have established isolation units and consulted with staff on handling anyone else with Ebola.

With eight children sent home from school because they had direct contact with the lone confirmed Ebola victim, Children’s Memorial Hospital in northwest Dallas is preparing for pediatric Ebola patients, and doctors at Parkland Memorial Hospital and Baylor University Medical Center have identified teams of doctors and nurses to be ready. As has become commonplace nationwide, the Dallas hospitals are screening incoming patients to see if they’ve traveled to West Africa within the last three weeks.

The U.S. Centers for Disease Control and Prevention has urged providers to be prepared, while also insisting that the United States isn’t likely to see the kind of outbreak that has killed thousands of people in Liberia, Sierra Leone and Guinea.

Mortality rates are likely to be much lower in countries with more sophisticated health care infrastructure, and Ebola also isn’t nearly as contagious as the flu, which can be spread through the air. Nor is it like HIV, which can be transmitted by people who have no symptoms.

Still, there is concern in some quarters that not enough is being done.

National Nurses United, representing about 185,000 nurses nationwide, has been surveying its union members an dfound that many don’t feel nurses are getting enough training to properly handle Ebola, union spokesman Charles Idelson said. Many said they didn’t know whether their hospital had protective gear, he said.

“It’s not enough to post a link to the Centers for Disease Control on the hospital’s website,” he added.

Wenzel, the infectious disease specialist, said officials should think beyond health care facilities. For instance, cab drivers might be given pamphlets urging them to ask sick passengers on trips to hospitals the same question being posed now by ambulance drivers and triage nurses: Have you traveled to West Africa lately?

“I wouldn’t put it in terms that are going to make people panic,” he said, but drivers should at least be wary of the health risks of cleaning up a mess left by a sick passenger.

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Associated Press writers Nomaan Merchant in Dallas and John Seewer in Toledo, Ohio, contributed to this report.